``` #include #include<bits/stdc++.h> using namespace std; typedef long long ll; int main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); ll n; ll flag; ll c; cin>>n; if(n==1) cout<<1; if(n==3)//n=3时循环读取不到，因为i从2开始，n至少为4，所以进行特判 cout<<"YES"; for(ll i=2;i<=sqrt(n);i++) { if(n%i==0) { flag=0; c=i; break; } else flag=1; } if(flag==1) cout<<"YES"; if(flag==0) cout<<n/c; return 0; } ```

```cpp // https://dashoj.com/p/98 #include <bits/stdc++.h> using namespace std; typedef long long ll; ll n, ans = -1; int main() { cin >> n; for (ll i = 2; i * i <= n; i++) if (n % i == 0) ans = max(ans, max(i, n / i)); if (ans == -1) cout << "YES" << endl; else cout << ans << endl; return 0; } ```

``` /* 思路： 思路一：1. 判断是否是质数 */ #include <bits/stdc++.h> using namespace std; int function_find(int n) { if ( n == 1 ) { cout << 1 << endl; return 1; } for ( int i = 2; i <= sqrt(n)+1; i++ )//循环判断是否是质数 (1 >> 根号n) if ( n % i == 0 ) { cout << (n/i) << endl; return 1; } cout << "YES" << endl; return 1; } int main() { int n; cin >> n; function_find(n); return 0; } ```

include include bool isPrime(int n) { if (n factor) { factor = n / i; } } return factor; } int main() { int n; std::cin >> n; ``` if (isPrime(n)) { std::cout << "YES" << std::endl; } else { int secondLargest = secondLargestFactor(n); std::cout << secondLargest << std::endl; } return 0; ``` }